the lymphatic system by-design-v1/the-lymphatic- system.html

The Lymphatic System

http://www.faqs.org/health/Body-by-Design-V1/The-Lymphatic-

System.html

The Lymphatic System

• The body is constantly in contact with bacteria, fungi, and viruses (all considered pathogens)

• The body has two defense systems for foreign materials

Types of Defense

• Non-Specific Defense

– First & Second Line of Defense

– Doesn’t care what the pathogen is – your body will be defended!

Non-Specific Defense

• Non-Specific Defense Mechanisms Include…– Skin: mechanical barrier, acidic skin secretions

can also defend– Mucous Membranes: Mucus and nasal hairs

trap microorganisms; Cilia move mucus out of body; Gastric juice, saliva, and tears have enzymes that destroy microorganisms

– Skin and Mucous Membranes are the first line of defense against pathogens

– Cellular & Chemical Defense: Second line of defense; includes…


• Phagocytes: • Cell that engulfs a

foreign particle, enclosing it in a vacuole; destroyed with enzymatic contents of lysosomes


• Examples of phagocytes include macrophages (in body tissues, developed from monocyte WBC), and neutrophils (WBC)

Macrophage engulfing E-Coli


• Natural Killer Cells: • Defensive cells that

can kill cancer cells and virus-infected body cells

• Release chemicals to destroy invader’s cell membrane and nucleus


• Inflammatory Response:• Non-specific response triggered whenever body

tissues are injured


• Benefits of inflammatory response include:– Preventing the spread of damaging agents to

nearby tissues– Disposes of cell debris and pathogens– Sets the stage for repair


• 4 Signs of Inflammatory Response:• Redness – due to dilation of blood vessels

in area, bringing more clotting proteins/ oxygen/nutrients to the area

• Heat – due to dilation of blood vessels in area, helps increase metabolic rate of cells

• Swelling – due to plasma (lymph) leaking from blood stream into tissue spaces

• Pain – pain receptors activated by plasma leaking


• All of the above symptoms are due to the inflammatory chemicals (including histamine and kinins) that are released when cells are damaged


• Fever: response to invading pathogens

• Hypothalamus will reset internal temperature based on presence of pyrogens (chemicals secreted by WBC exposed to foreign substances)

• Fever inhibits the release of iron and zinc from liver and spleen needed by bacteria

• Fever also increases the speed of tissue repair, but if fever gets too high, it can screw up enzymes and proteins

Specific Defense• Specific Defense

– Third line of defense

– AKA immune system

– Plans defense based on specific type of pathogen/antigen (The antigen is a marker on the pathogen!)

– Must first have an initial exposure before it can protect the body against the pathogen

– Involves the Lymph Vessels/Nodes and Lymphoid Organs (Tonsils, Thymus, Spleen, and Peyer’s Patches)

Specific Defense

• 2 Types of Response: Humoral and Cell-Mediated

Specific Defense

• 3 important aspects of immune response:

• Antigen specific – recognizes and acts against particular foreign substances

• Systemic – not restricted to the initial infection site

• Has memory – recognizes and mounts a stronger attack on previously encountered pathogens

Specific Defense

• Antigens: any substance capable of exciting our immune system and provoking an immune response

• A foreign signal on the outside of a pathogen!• Examples of common pathogens/antigens

– Foreign proteins (ex: blood typing)– Pollen grains– Microorganisms (bacteria, fungi, virus)

• Side Note: Our immune cells do not attack our own proteins, but our cells in another person’s body can trigger an immune response because they are foreign (think: organ transplants, blood donation)

Immune System Review

– Types of cells involved

• Lymphocytes (WBC): two types…

–B Cells: help with humoral defense, produce antibodies

–T Cells: help with cell-mediated defense, do not produce antibodies

Specific Defense

• Both types of lymphocytes originate from red bone marrow

• What determines if it will be a B or T cell is where in the body it becomes immunocompetent (capable of responding to a specific antigen)– T Cells: lymphocytes migrating to thymus– B Cells: lymphocytes develop in bone marrow

Specific Defense

• Our genes determine what specific foreign substances our immune system will be able to recognize and resist – they only become “activated” once exposed to the antigen

• FYI: Because of the structure of human DNA (deoxyribonucleic acid; the genetic material determining the makeup of all cells), humans are not subject to certain diseases that dogs and other animals are, and vice-versa. For example, humans cannot contract distemper; however, dogs and cats can. Conversely, humans can suffer from measles; dogs and cats cannot. The genetic makeup of human cells (and of animal and plant cells, also) makes it impossible for certain pathogens to infect and reproduce in those cells.

Specific Defense

• After becoming immunocompetent, both T and B cells migrate to the lymph nodes and spleen, but can be found throughout lymphatic vessels

Specific Defenses

• Macrophages:

• Arise from monocytes (WBC) formed in the bone marrow

• Job is to engulf foreign particles (part of non-specific defense) and present fragments of these antigens on their surface (so T Cells can recognize them and become activated, helping out specific defense!)

Humoral Defense

• Making the Antibodies

– B Cells with specific receptors bind to a specific antigen

– …which causes the B Cell to undergo “clonal selection” – a whole bunch of clones are made!

Humoral Defense

– Most of the clones will become “plasma cells”, which are responsible for producing specific antibodies!

– A few of the clones will become “memory cells”, which will be ready to bind with the antigen if it should come around again

Humoral Defense

• Antibodies– Soluble proteins

secreted by B cells (plasma cells)

– Carried in blood plasma

– Usually has a T or Y shape formed by amino acid chains

– Capable of binding specifically to an antigen

Humoral Defense

• When antibodies attach to antigens, it can have different effects…

Humoral Defense

– Complement Fixation: antibody will join with a “complement protein” on the invader; which will allow holes on the invader surface; will result in cell lysis (bursting of cell)

Humoral Defense

– Neutralization: surrounds antigen to mask its effects

Humoral Defense

– Agglutination: clumping of antigens; will allow macrophages to easily catch and engulf invaders

Cell Mediated Defense

• Begins with macrophages destroying an antigen

• Macrophage will then put fragments of the destroyed antigen on the outside

• T Cells will recognize the antigen being presented by the macrophage and bind with the antigen (Antigen Presentation)

• After binding, T Cell clones form, but different classes of cells are produced


• Cytotoxic T Cell: “killer” cells, specialize in killing virus-infected, cancer, and foreign cells, often by inserting toxic chemicals, causing the pathogen cell to “blow up”

Note: basically does the same thing as a Natural Killer Cell, but does it to a specific pathogen!

http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter24/animation__cytotoxic_t-cell_activity_against_target_cells__quiz_2_.html


• Helper T Cell: “regulator/conductor” cells, encourages cloning of B cells, stimulates Cytotoxic T Cells to grow and divide, enhances eating capabilities of macrophages


• Supressor T Cell: helps to stop immune response once an antigen has been inactivated or destroyed

• http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter24/animation__the_immune_response.html

Viruses

• Not considered “living” because has no cytoplasm or organelles

• Needs a living host cell to survive

• Will take over host cell to replicate

• Virus infections cannot be treated with antibiotics

• Some can be prevented with vaccines

Viruses• Common Cold• Varicella - Chicken Pox – rarely fatal• Variola – Smallpox – often fatal – but now

eliminated thanks to vaccinations!• Influenza – MANY different strains!• Human Papillomavirus – HPV – can lead to

warts, cervical cancer, and some other genital cancers

• Rotavirus – leading cause of diarrhea among infants and young children

Smallpox

Chicken Pox

Viruses

• Mumps – swelling of salivary glands, and testicular swelling

• Measles – can lead to diarrhea, pneumonia, encephalitis, and eye infections

• Rubella – rash• Poliomyelitis – in less than 1% of polio cases, virus

enters the CNS, destroying motor neurons, leading to muscle weakness and paralysis; highly contagious

• Rabies – causes encephalitis; extremely fatal• HIV

Rubella

Measles

Mumps

MMR Vaccination protects against

all three!

Vaccination

• Administration of antigenic material to produce immunity to a disease

• Can be live but weakened, dead, or inactivated form of pathogen (virus or bacteria)

• Pathogens are grown in culture and killed/weakened, but surface proteins are intact enough to be recognized

• When injected, immune system will evoke a response

• Are considered a “living” prokaryotic cell

• Does not need a living host cell to survive

• Most (99%) are good, but a few are harmful– Good ones help us with digestion, releasing

vitamins, eliminating body toxins, preventing fungal growth

Bacteria

• Harmful bacterial infections can be treated with antibiotics

• Some can live harmlessly, but develop into an infection if immune system has had its resistance lowered (ex: AIDS)

• A few infections can be prevented with vaccines

Bacteria

Bad Bacteria

• Tuberculosis – affects lungs• Streptococcus – affects throat (pharynx,

larynx, tonsils)• Botulism – weakens muscles, prevents

breathing• Bubonic Plague – spread by fleas that live

on rats; damages lymph notes• Cholera – affects small intestine, causes

diarrhea, vomiting, and rapid dehydration

Bad Bacteria

• Salmonella – can cause digestive issues

• Escherichia Coli – aka E.Coli – some strains are good, but the bad strains can cause lower digestive issues or UTIs

• Syphilis – STD that causes lesions; if left untreated, it can cause issues with the heart and brain

• Impetigo – skin infection

Bad Bacteria

• Diphtheria – causes upper respiratory issues

• Pertussis – whooping cough

• Tetanus – causes muscle spasms

• These last three can be quite harmful (even deadly) that we are given the DPT vaccination

Antibiotics

• A substance or compound that kills or inhibits growth of bacteria

• Can either be made synthetically from chemicals or produced by fermenting different fungus molds

• Unfortunately, bacteria can mutate to become resistant to antibiotics

• EX: penicillin, amoxicillin, tetracycline, sulfa drugs, cefzil

Fungus

• Are considered a “living” eukaryotic cell

• Includes molds and yeasts

• Some are good, such as fungi used to make antibiotics (penicillin) or baker’s yeast

• Infections can spread very easily!

Bad Fungi

• Candida – Yeast Infection

• Tinea Pedis – Athlete’s Foot

• Tinea Cruris – Jock Itch

• Tinea Unguium – Nail Fungus

Immune System Diseases

• Allergies– Abnormally vigorous immune responses– Different types…

Immune System Diseases - Allergies

– Acute hypersensitivity

• Pathogen & resulting antibodies cause release of histamine…

• Which causes small blood vessels to become dilated and leaky

• Symptoms include runny nose, watery eyes, itching, reddened skin (hives), bronchial constriction (asthma)

• Antihistamine drugs can reverse effects

Immune System Diseases - Allergies

– Anaphylactic Shock

• Allergen directly enters the blood and circulates rapidly throughout the body

• Examples: Bee stings, spider bites, drug injections

• Dilated & leaky blood vessels throughout body can be life-threatening

• The drug Epinephrine can reverse effects


• Immunodeficiencies

– Production or function of immune cells is abnormal

– May be congenital or acquired

– Examples include…

Immune System Diseases - Immunodeficiencies

• Severe Combined Immunodeficiency Syndrome (SCIDS)

– Deficit of both B and T cells

– Have no immune response

– “Bubble Boy” Disease

– Some success with bone marrow transplants

For twelve years David Vetter, born with combined immune deficiency, lived inside this plastic bubble at

Texas Children's Hospital in Houston, Texas, waiting for a cure to the disease that kept him prisoner.


• Acquired Immune Deficiency Syndrome (AIDS)

– The virus (Human Immunodeficiency Virus, or HIV) destroys Helper T Cells & Macrophages

– Cell-mediated immunity is reduced

– Virus then begins to multiply in lymph nodes – which takes longer in some than in others


– A patient is diagnosed with AIDS when the lymph nodes are destroyed & symptoms begin

– Symptoms include severe weight loss, night sweats, swollen lymph nodes, and increasingly frequent infections (gastrointestinal, pneumonia)

– Some of the drugs that are used to help act by inhibiting the enzymes the HIV virus needs in order to multiply, or helps to boost number of Helper T Cells

– THERE IS NO CURE OR VACCINE.


• Facts:

– 33.2 million worldwide have AIDS; 2.5 million are children under age 15

– 1.9 million died of AIDS in 2010; 330,000 were children under age 15

– Sub-Sahara Africa contains 68% of the AIDS population

– The median survival time after infection with HIV is estimated to be 9 to 11 years, depending on the HIV subtype


• Autoimmune Diseases– The immune system does not distinguish

between self and non-self– The body produces antibodies and T Cells

that attack its own tissues– Examples Include…

Immune System Diseases - Autoimmune Diseases

– Multiple sclerosis: myelin sheaths in the white matter of brain & spinal cord are destroyed

– Type 1 diabetes: destroys pancreatic beta cells that produce insulin

– Rheumatoid arthritis: destroys joints– Lupus: affects kidney, heart, lung and skin

the lymphatic system by-design-v1/the-lymphatic- system.html

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